Silicon-CNT Composite for High Energy Density Li-Ion Batteries

Wednesday, 31 May 2017
Grand Ballroom (Hilton New Orleans Riverside)
L. K. Ventrapragada, P. Parajuli, A. B. Kousaalya, S. Pilla, R. Podila, and A. M. Rao (Clemson University)
Rechargeable batteries (e.g., Li-ion) are widely used to power a number of portable electronic devices such as mobile phones and laptops. Li-ion batteries (LIBs) in particular have revolutionized electric vehicle technology, nonetheless, they suffer from poor energy and power densities, which ultimately limit the driving range and increase the cost. Recently, silicon (Si) anode has attracted a considerable attention from battery researchers as an alternative to conventional graphite anode due to its high specific capacitance (4200 mAh g-1) corresponding to Li22Si5. However successful commercialization of Si anodes in battery packs is hindered by the irreversible capacity loss during cycling associated with volume expansion (~300%), finally leading to electrode failure. In recent times, there have been a number of reports claiming high specific capacities for Si composites but they involve complex synthesis steps leading to higher cost. In this poster, we will discuss our approach of making a composite with CNTs and commercial Si using ultrasonication method. Carbon nanotubes (CNTs) have excellent electrical conductivity and mechanical stability. The composite electrodes when assembled into a battery showed excellent electrochemical performance: albeit small losses in coulombic efficiency during initial six cycles, they retained 100% efficiency for more than 150 cycles. This could be attributed to the inclusion of CNTs which form a flexible network around Si particles, and facilitates volume expansion/contraction during reduction/oxidation of the electrode. Such modification of Si anodes can be seamlessly integrated into commercial manufacturing.